Shock absorber construction



at. 24, 1944. R. H. WHISLER, JR

SHOCK ABSORBER CONSTRUCTION Filed Aug. 3, 1942 INVENTOR. RALPH H. WHISLER JR.

ATTORNEYS Patented Oct. .24, 1944 UNITED STATES PATENTfOFFICE a "2,360,993 I SHOCK ABSORBER CONSTRUCTION Ralph H. Whisler. Jr., Monroe, Mich. ,assignor'to Monroe Auto Equipment Company, Monroe, Mich., a corporation of Michigan Application August 3, 194,2,Serial No. 453,412

1 Claim. 7 (01. 1ss-'-.ss) I This invention relates to hydraulic shock absorbers of the tubular direct acting type having a cylinder adapted to contain a suitable fluid and having a piston reciprocably mounted in the cylinder.

Although shock absorbers of the above general type may be advantageouslyemployedin practically any case where it is desired to control relative movementbetween a pair of relatively movable parts, nevertheless, they are especially applicable to vehicles for controlling relative movement between the sprung and unsprung vehicle assemblies.

Considerable diiiiculty has been encountered in the past in providing a shock absorber having the flexibility and control required to afford the optimum results'under widely varying conditions. Due to the design characteristics of conventional types of shock absorbers, relatively slight movements of the unsprung assembly are substantially damped or resisted, especially if they occur in rapid succession and the force reaction resulting from this damping action of the shock absorbers is transferred to the sprung assembly in the form of vibrations which detrimentallyeii ect the riding qualities of the vehicle.

In accordance with the present invention, the

above objection is overcome by providing a shock absorber constructed in such a manner that very little or no resistance is afiorded tonormal or Another object of this invention is to provide a shock absorber having a ported piston and having a valve responsive to relatively high accelerations of the piston on the rebound stroke to close the ports through the piston and thereby prevent or' substantially minimize the long amplitudes' which usually result from high initial accelerations of the piston.

A still further feature of this .inventionis to provide a shock absorber having means for also substantially restricting relatively fast initial movement of the piston on the compression stroke.

The foregoing, as well as other objects, will be made more apparent when this description proceeds, especially when considered in connection with the accompanying drawing, wherein:

Figure 1 is a longitudinal sectional view showing a shock absorber constructed in accordance with this invention; and

place.

Figure 2 is a cross sectional view taken on the plane indicated by'the line'2-'2 of Figure 1.

I Figure 3 is a cross sectional view taken substantially online 33 of Figure 1.

i In Figure 1 of the drawing I have illustrated a'hydraulic-shock absorber of the direct acting tubular type having a cylinder. I0 and having a tube I I surrounding the cylinder in concentric relation thereto. The internal diameter of the tube II is substantially greater than the outside diameter of the cylinder") and cooperates-with the latter to form an annular reserve chamber I2.

The lower end of the reserve chamber I2 is closed by a cap i3 having ports I4 establishing communication between the lower end of the reserve chamber I2 and the corresponding end of the cylinder III. The 'cap I3 is also provided with a fixture I5 of a design which enables the same to be readily pivotallyconnected to one of a pair of relatively movable parts, not shown herein. In the present instance, the fixture I5 is adapted to be pivotally connected to the unsprung assembly of a vehicle and any one of a number of accepted methods may be employed for accomplishing this result.

The upper end of thecylinderIO is closed by a head I6 having an enlarged portion IT at the upper end of 'suflicient diameter to frictionally engage the inner surface of the tube I I and having a reduced portion I8 secured to theupper end of the cylinder I0. The head I6 is secured v in'place by means of a ring I9 which is threadedly mounted in the upper end of the tube II above the enlargement I! and cooperates with this enlargement to'clamp'a suitable seal 20 in The seal 20 coacts with the enlargement I! to close the upper end of the reserve chamber I2 and to prevent escape of fluid from the reserve chamber.

It will also be noted from Figure l of the drawing that the head I6 is formed with a centrally arranged bore 2! of sufficient diameter to slidably receive a piston rod 22 having the lower end operatively connected to a-piston 23. The

piston 2 3 occupies a position in the cylinder I0 "and slidably engages the inner surface of the are of suflicient internal diameter to enable relatively free flow of fluid therethrough during movepressure in the cylinder below the piston rises at the beginning of downward travel of the piston rod. This is due to the displacement of the piston rod 22 which causes the volume of the portion of the cylinder below the piston to diminish at a faster rate than the rate at which the volume above the cylinder increases. In the present instance, the excess fluid in the cylinder below the piston is discharged into the reserve chamber I2 through the ports 14 and the rate of escape of this fluid is controlled to provide a damping action on ment of the piston 23 in opposite directions. In

accordance with this invention the portsare controlled by a single slide valve 28 'slidably mounted on the piston rod 22 abovethe piston 23. .In detail, it will be noted that the valve 28 is mounted on a, reduced portion 29 of the' piston rod 22 for continued downward travel of the piston 23 in .the cylinder.

Also by reason of the displacement of the piston rod 22, it is necessary to replenish the cylinder with fluid when the piston moves in an upward direction in the cylinder and this transfer of fluid is also accomplished by the ports M. In

sliding movement between the upper surfaceof the piston and an annular shoulder 30 'formed onthe piston rod by thereducedportion 29.

The valve 28 is normally .heldin its open or uppermost positionagainst the shoulder-30 by means of a coilspring 3|. The coil spring 3! surrounds the reduced portion '29 "of the piston rod 22 and the opposite ends of the spring respectively engage-the top surface of the piston 23 and the'adjacent surface 'of the valve. 'As shown particularly in Figure 2 of the drawing, the central portion of the valve'28 is ,formed with a plurality of openings 33 therethrough to'facilitate the passageof fluid through the. ports 21 when the. valve is in its open position.

It follows from the above that if the piston 23'is relatively moved at a normal rate in anupward direction fromthe positionshown in Figure 1, fluid in the portion of the; cylinder above the piston is permitted to flow to the portion of the cylinder below the, piston through the ports 21. The combined cross sectional area of the ports 21 is suchthat very little or no resistance'is offered to the passage of fluid through the piston and, as

'a consequence, the piston is relatively moved in an upward direction at a substantially unretarded rate until the pressure; in the portion of the cylinder l0 above thepiston exceeds the force of the spring 3|. When this condition exists, the valve 28 is forced downwardly toits closed position with respect to all of th ports 2'! and continued upward movement of the piston is highly resisted. It will, of course, be understood that the action of 1 the spring His also overcome and the valve 28 is closed if for any reason upward movement of the piston is initiated at a high or I abnormal velocity. As a consequence, the usual long amplitud resulting .from this action is avoided and far superior riding qualities are this instance, however, fluid'is permitted to flow relatively freely from the reserve chamber through the ports I4 into the lower end of the cylinder.

I As shown in Figure 1, the transfer of .fiuid between the reserve chamber and cylinder is con.- trolled in both the .aboveinstances by a compound valve 34. The valve 34 is secured in the lower end of the cylinder l0 and comprises a plate 35 having two sets of ports 36 and 31 therethrough. The outer set of ports 36 is normally closed by a disc valve 38 clamped at its center on the top surface of the plate and normally urged to its closed position by a light substantially star shaped spring 39. The arrangement is such that when the piston is relatively moved in an upward direction, fluid is permitted to flow relatively freely from the reserve chamber to the cylinder in amounts necessaryto compensate for the increased volume of the cylinder below the piston which results from the displacement of the piston rod 22.

The inner set of ports 31 is closed by a laminated .disc valve 40 clamped at its center against the bottom surface of the plate 35 by means of a. suitable fastener element 4!. .The valve Minis opened by the pressure rise in the lower end of the cylinder as the piston is moved in a downward direction and the pressure required to open this valve is sufilciently high to produce a substantial retarding effect on the piston. rod as-it approaches the lower endof the cylinder 10.

What I claim as my invention is: I

A direct acting hydraulic shock absorber having a cylinder, a reserve chamber communicating with the cylinder adjacent one end of the latter, a piston in said cylinder having a port therethrough permitting relatively free flow of fluid through the piston as the latter moves in opposite'directions in the cylinder, valve for the port supported for sliding movement relative to the piston at the side of said piston opposite the side facing the point of communication between the reserve chamber and cylinder, said valve being engageable with the piston to close the port therein, yieldable means acting on said valve normally maintaining the latter in its open position, and a pressure operated valve for closing communication between the cylinder and reserve chamber.

RALPH H. W'HISLER; JR. 

